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dm delay: fix a possible deadlock due to shared workqueue

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The dm-delay target uses a shared workqueue for multiple instances.  This
can cause deadlock if two or more dm-delay targets are stacked on the top
of each other.

This patch changes dm-delay to use a per-instance workqueue.

Cc: stable@vger.kernel.org # 2.6.22+

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2013-11-15 16:12:20 -05:00 committed by Mike Snitzer
parent 7b6b2bc98c
commit 718822c1c1
1 changed files with 11 additions and 12 deletions
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23
drivers/md/dm-delay.c
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@ -20,6 +20,7 @@
struct delay_c {
struct timer_list delay_timer;
struct mutex timer_lock;
struct workqueue_struct *kdelayd_wq;
struct work_struct flush_expired_bios;
struct list_head delayed_bios;
atomic_t may_delay;
@ -45,14 +46,13 @@ struct dm_delay_info {
static DEFINE_MUTEX(delayed_bios_lock);
static struct workqueue_struct *kdelayd_wq;
static struct kmem_cache *delayed_cache;
static void handle_delayed_timer(unsigned long data)
{
struct delay_c *dc = (struct delay_c *)data;
queue_work(kdelayd_wq, &dc->flush_expired_bios);
queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
}
static void queue_timeout(struct delay_c *dc, unsigned long expires)
@ -191,6 +191,12 @@ out:
goto bad_dev_write;
}
dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
if (!dc->kdelayd_wq) {
DMERR("Couldn't start kdelayd");
goto bad_queue;
}
setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
@ -203,6 +209,8 @@ out:
ti->private = dc;
return 0;
bad_queue:
mempool_destroy(dc->delayed_pool);
bad_dev_write:
if (dc->dev_write)
dm_put_device(ti, dc->dev_write);
@ -217,7 +225,7 @@ static void delay_dtr(struct dm_target *ti)
{
struct delay_c *dc = ti->private;
flush_workqueue(kdelayd_wq);
destroy_workqueue(dc->kdelayd_wq);
dm_put_device(ti, dc->dev_read);
@ -350,12 +358,6 @@ static int __init dm_delay_init(void)
{
int r = -ENOMEM;
kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
if (!kdelayd_wq) {
DMERR("Couldn't start kdelayd");
goto bad_queue;
}
delayed_cache = KMEM_CACHE(dm_delay_info, 0);
if (!delayed_cache) {
DMERR("Couldn't create delayed bio cache.");
@ -373,8 +375,6 @@ static int __init dm_delay_init(void)
bad_register:
kmem_cache_destroy(delayed_cache);
bad_memcache:
destroy_workqueue(kdelayd_wq);
bad_queue:
return r;
}
@ -382,7 +382,6 @@ static void __exit dm_delay_exit(void)
{
dm_unregister_target(&delay_target);
kmem_cache_destroy(delayed_cache);
destroy_workqueue(kdelayd_wq);
}
/* Module hooks */